1. Field of the Invention
The present invention relates to a magnetic tape cartridge and more particularly relates, in a magnetic tape cartridge where a single reel with magnetic tape wound thereon is rotatably housed within a cartridge case, to the structure of reel-rotation restraining means which causes the reel to be in a rotation-restrained state when not being used.
2. Description of the Related Art
In the magnetic tape cartridges, which are used as storage medium to be employed in external storage units for computers, etc., there is known a type where a single tape reel with magnetic tape wound thereon is rotatably housed within a cartridge case. This magnetic tape is employed as a data archiving tape for computers, etc., and stores important information. For this reason, the magnetic tape cartridge is provided with reel-rotation restraining means for restricting rotation of the reel so that problems, such as tape jamming, etc., do not occur and that the magnetic tape is not pulled out from the cartridge case unexpectedly when not being used, such as when being archived, etc.
The reel-rotation restraining means, as disclosed in Japanese Unexamined Patent Publication No. 11 (1999)-23835, is equipped with a restraining member for restricting rotation of the reel, an urging member for urging the restraining member in a restraining direction, and an unlocking member for moving the restraining member in an unlocking direction in accordance with the chucking operation of the rotation means of the drive mechanism of a drive unit such as a recording-reproducing unit.
A locking tooth portion is formed on the reel side, while a restraining gear meshable with the locking tooth portion is provided on the side of the restraining member provided so that it cannot rotate with respect to the cartridge case. In the non-operative state, the restraining gear of the restraining member engages the locking tooth portion of the reel to restrict unexpected rotation of the reel, whereby the magnetic tape wound on the reel can be locked. On the other hand, if the magnetic tape cartridge is loaded into the drive unit, the unlocking member moves the restraining member to disengage the restraining gear of the restraining member from the locking tooth portion of the reel. In the disengaged or unlocked state, the reel is rotatable and therefore the magnetic tape can be loaded into or unloaded from the drive unit.
The above-mentioned unlocking member is equipped with a main body which abuts the above-mentioned restraining member, and leg portions which abut the rotation means of the drive mechanism of the drive unit. When the chucking operation of the rotation means is performed, the rotation means moves the unlocking member upward to disengage the retraining gear of the restraining member from the locking tooth portion of the reel.
In the case where a magnetic tape cartridge is equipped with the reel-rotation restraining means mentioned above, incidentally, the restraining member in the unlocked state is unstable because the central portion of the restraining member is supported only by the central portion of the unlocking member. On the other hand, because the reel is rotated or stopped according to loading or unloading of the magnetic tape, the force exerted on the reel is transmitted to the restraining member through the unlocking member. For this reason, the restraining member tends to tilt. If the restraining member tilts, the restraining gear thereof will contact the locking tooth portion of the reel. This produces an undesirable sound, disturbs rotation of the reel, and interferes with the operation of loading or unloading magnetic tape.
In addition, in the case where the magnetic tape slackens because of the shock produced by the magnetic tape cartridge falling when not being used, the magnetic tape cartridge cannot absorb the slack of the magnetic tape because it has only a single reel within the cartridge case. As a result, there is a fear that the magnetic tape will be damaged. Hence, in order to prevent the magnetic tape from slackening because of shock caused by the cartridge falling, the locking tooth portion of the reel and the restraining gear are constructed so that the tooth face of the locking tooth portion, which faces in the reverse winding direction (tape slackening direction), and the tooth face of the restraining gear, which abuts the tooth face of the locking tooth portion, are inclined at an angle near to 90 degrees.
However, in the case where the reel in the non-operative state is unexpectedly locked by the mesh between the restraining gear and the locking tooth portion, there are cases where the reel is freely moved by the complete mesh between the restraining gear and the locking tooth portion, depending on the phase relationship between the two in the unmeshed state. Particularly, if the tooth face of the locking tooth portion, which faces in the reverse winding direction (tape slackening direction), and the tooth face of the restraining gear, which abuts the tooth face of the locking tooth portion, are inclined at an angle near to 90 degrees in order to prevent slackness, as described above, the locking tooth portion and the restraining gear move only in the winding direction when they mesh with each other, and consequently, force is exerted on the magnetic tape in the winding direction.
In addition, in the case of a magnetic tape cartridge with magnetic tape wound on a single reel, a tape leader member is coupled with the leading end of the magnetic tape, and the tape leader member is caught by the catching member of the drive mechanism of a drive unit to pull out the magnetic tape from the cartridge case. In this construction, if the tape leader member is exposed to the case peripheral side, there is a problem that the free end will project from the cartridge case, or dust will enter the cartridge case through a tape leader opening formed in the cartridge case, when the magnetic tape cartridge is subjected to a falling shock, etc. Hence, it is disclosed in Japanese Unexamined Patent Publication No. 11 (1999)-232828 that a tape leader pin is retained inside a tape leader opening which is closed or opened by a slide door. The configuration of the tape leader member is determined mainly by specifications for the recording-reproducing unit.
Thus, in the case where the tape leader pin is coupled with the leading end of the magnetic tape, and the tape leader pin is retained within the cartridge case during the non-operative state, if the reel is moved in the winding direction and a pulling force greater than a predetermined quantity is exerted on the magnetic tape, there is a fear that the magnetic tape and the tape leader pin will be easily disengaged from each other, because the strength of the engagement of the tape leader pin with the magnetic tape is relatively low. Even when the two are not disengaged, the magnetic tape will be stretched by the aforementioned pulling force. Because of this, the magnetic recording-reproducing characteristics are degraded, or the tape leader pin is shifted out of a predetermined retaining position or tilted. Thereafter, there is a fear that the magnetic tape cannot be correctly loaded into the drive unit and therefore reliability will be reduced.
The present invention has been made in view of the above-mentioned points. Accordingly, it is a first important object of the present invention to provide a magnetic tape cartridge which is capable of preventing the contact between a restraining gear and a locking protrusion that is caused by the tilt of the restraining member.
A second important object of the invention is to provide a magnetic tape cartridge that is capable of preventing the disengagement of the magnetic tape from a tape leader pin which is caused by the magnetic tape pulled in the locked state when subjected to a falling shock, while assuring the locked state of a reel obtained in a non-operative by the restraining member of reel-rotation restraining means.
To achieve the first object of the present invention and in accordance with the present invention, there is provided a first magnetic tape cartridge comprising:
a cartridge case where a single reel with magnetic tape wound thereon is rotatably housed; and
reel-rotation restraining means which, when not used, goes to a locked state to restrict rotation of the reel and, when used, goes from the locked state to an unlocked state to allow the rotation; the reel-rotation restraining means having a restraining member for restricting rotation of the reel by moving toward or away from the reel, an urging member for urging the restraining member in a restraining direction, and an unlocking member for moving the restraining member in an unlocking direction, by rotating integrally with the reel and moving according to a chucking operation of rotation means of a drive unit;
wherein the restraining member has a restraining gear which meshes with a locking tooth portion formed in the reel to restrain rotation of the reel, the restraining member being supported by a support portion of the cartridge case so that it is slidable without being rotated; and
the following relationship is met:
bxe2x89xa6(2xc3x97axc3x97c)/d
where xe2x80x9caxe2x80x9d represents the length of engagement between the restraining member in the unlocked state and the support portion, xe2x80x9cbxe2x80x9d represents the clearance between the restraining member and the support portion, xe2x80x9ccxe2x80x9d represents the space between a tooth of the restraining gear and the locking tooth portion, and xe2x80x9cdxe2x80x9d represents the outside diameter of the restraining gear.
In accordance with the present invention, there is provided a second magnetic tape cartridge comprising:
a cartridge case where a single reel with magnetic tape wound thereon is rotatably housed; and
reel-rotation restraining means which, when not used, goes to a locked state to restrict rotation of the reel and, when used, goes from the locked state to an unlocked state to allow the rotation; the reel-rotation restraining means having a restraining member for restricting rotation of the reel by moving toward or away from the reel, an urging member for urging the restraining member in a restraining direction, and an unlocking member for moving the restraining member in an unlocking direction, by rotating integrally with the reel and moving according to a chucking operation of rotation means of a drive unit;
wherein the reel has a reel gear which meshes with a driving gear of drive means of the drive unit;
the unlocking member has a main body which abuts the restraining member, and leg portions whose lower ends abut part of the drive means of the drive unit through guide holes provided to penetrate the reel gear; and
in the locked state, the lower ends of the leg portions of the unlocking member project from a tooth edge of the reel gear.
In accordance with the present invention, there is provided a third magnetic tape cartridge comprising:
a cartridge case where a single reel with magnetic tape wound thereon is rotatably housed; and
reel-rotation restraining means which, when not used, goes to a locked state to restrict rotation of the reel and, when used, goes from the locked state to an unlocked state to allow the rotation; the reel-rotation restraining means having a restraining member for restricting rotation of the reel by moving toward or away from the reel, an urging member for urging the restraining member in a restraining direction, and an unlocking member for moving the restraining member in an unlocking direction, by rotating integrally with the reel and moving according to a chucking operation of rotation means of a drive unit;
wherein the restraining member has a restraining gear which meshes with a locking tooth portion formed in the reel to restrain rotation of the reel, the restraining member being supported by a support portion of the cartridge case so that it is slidable without being rotated; and
in the unlocked state, the space between a tooth of the restraining gear and the locking tooth portion is set to a length greater than or equal to a tooth depth of the restraining gear.
In the third magnetic tape cartridge, it is preferable that the aforementioned space be set greater than or equal to 1.2 times the tooth depth of the restraining gear. It is further preferable that the aforementioned space be set greater than or equal to 1.4 times the tooth depth of the restraining gear.
In accordance with the present invention, there is provided a fourth cartridge case where a single reel with magnetic tape wound thereon is rotatably housed; and
reel-rotation restraining means which, when not used, goes to a locked state to restrict rotation of the reel and, when used, goes from the locked state to an unlocked state to allow the rotation; the reel-rotation restraining means having a restraining member for restricting rotation of the reel by moving toward or away from the reel, an urging member for urging the restraining member in a restraining direction, and an unlocking member for moving the restraining member in an unlocking direction, by rotating integrally with the reel and moving according to a chucking operation of rotation means of a drive unit;
wherein either a slide portion of the restraining member or a slide portion of the unlocking member is formed into a curved surface which has a radius of curvature of 30 mm or less.
In the fourth magnetic tape cartridge, it is preferable that the radius of curvature of the curved surface be 20 mm or less. It is further preferable that the radius of curvature of the curved surface be 15 mm or less.
In accordance with the present invention, there is provided a fifth magnetic tape cartridge comprising:
a cartridge case where a single reel with magnetic tape wound thereon is rotatably housed; and
reel-rotation restraining means which, when not used, goes to a locked state to restrict rotation of the reel and, when used, goes from the locked state to an unlocked state to allow the rotation; the reel-rotation restraining means having a restraining member for restricting rotation of the reel by moving toward or away from the reel, an urging member for urging the restraining member in a restraining direction, and an unlocking member for moving the restraining member in an unlocking direction, by rotating integrally with the reel and moving according to a chucking operation of rotation means of a drive unit;
wherein the restraining member has a restraining gear which meshes with a locking tooth portion formed in the reel to restrain rotation of the reel;
the urging member is supported by a spring receiver formed in the cartridge case; and
the following relationship is met:
exe2x89xa6(2xc3x97fxc3x97c)/d
where xe2x80x9ccxe2x80x9d represents the space between a tooth of the restraining gear in the unlocked state and the locking tooth portion, xe2x80x9cdxe2x80x9d represents the outside diameter of the restraining gear, xe2x80x9cexe2x80x9d represents the clearance between an outer periphery of the urging member and an inner periphery of the spring receiver, and xe2x80x9cfxe2x80x9d represents the length of engagement between the urging member and the spring receiver.
To achieve the aforementioned second object of the present invention and in accordance with the present invention, there is provided a sixth magnetic tape cartridge comprising:
a cartridge case where a single reel with magnetic tape wound thereon is rotatably housed; and
reel-rotation restraining means which, when not used, goes to a locked state to restrict rotation of the reel and, when used, goes from the locked state to an unlocked state to allow the rotation; the reel-rotation restraining means having a restraining member for restricting rotation of the reel by moving toward or away from the reel, an urging member for urging the restraining member in a restraining direction, and an unlocking member for moving the restraining member in an unlocking direction, by rotating integrally with the reel and moving according to a chucking operation of rotation means of a drive unit;
wherein the restraining member has a restraining gear which meshes with a locking tooth portion formed in the reel to restrain rotation of the reel; and
a tooth of the restraining gear has two inclined faces which have an apex angle and interior angles, the apex angle being between an apex angle of the locking tooth portion of the reel and 90 degrees, and the interior angles being 30 degrees or greater with respect to a vertical line and also being approximately the same.
Note that the aforementioned vertical line refers to a line vertical to the direction of rotation of the reel. Also, in the sixth magnetic tape cartridge, it is preferable that the locking tooth portion and the tooth of the restraining gear be formed from synthetic resin material.
The present invention has the following advantages:
(1) In the reel-rotation restraining means, which has a restraining member for restricting rotation of the reel by moving toward or away from the reel, an urging member for urging the restraining member in a restraining direction, and an unlocking member for moving the restraining member in an unlocking direction, by rotating integrally with the reel and moving according to a chucking operation of rotation means of a drive unit,
the following relationship is met:
xe2x80x83bxe2x89xa6(2xc3x97axc3x97c)/d
where xe2x80x9caxe2x80x9d represents the length of engagement between the restraining member in the unlocked state and the support portion, xe2x80x9cbxe2x80x9d represents the clearance between the restraining member and the support portion, xe2x80x9ccxe2x80x9d represents the space between a tooth of the restraining gear and the locking tooth portion, and xe2x80x9cdxe2x80x9d represents the outside diameter of the restraining gear; or the following relationship is met:
exe2x89xa6(2xc3x97fxc3x97c)/d
where xe2x80x9ccxe2x80x9d represents the space between a tooth of the restraining gear in the unlocked state and the locking tooth portion, xe2x80x9cdxe2x80x9d represents the outside diameter of the restraining gear, xe2x80x9cexe2x80x9d represents the clearance between an outer periphery of the urging member and an inner periphery of the spring receiver, and xe2x80x9cfxe2x80x9d represents the length of engagement between the urging member and the spring receiver. With this arrangement, tilting of the restraining member is suppressed in the unlocked state. Therefore, the contact between the restraining gear and the locking tooth portion can be prevented and the major causes of an undesirable sound and a hindrance to the rotation of the reel can be eliminated.
(2) In the locked state, the lower ends of the leg portions of the unlocking member project from the tooth edge of the reel gear. Also, in the unlocked state, the space between the tooth of the restraining gear and the locking tooth portion is set to a length greater than or equal to the tooth depth of the restraining gear. With this arrangement, the extent of movement of the restraining member in the unlocked state increases. Therefore, even if the restraining member tilts slightly, the contact between the restraining gear and the locking tooth portion can be prevented and the major causes of an undesirable sound and a hindrance to the rotation of the reel can be eliminated.
(3) Either a slide portion of the restraining member or a slide portion of the unlocking member is formed into a curved surface which has a radius of curvature of 30 mm or less. With this, when the restraining member tilts, restoring force to a flat state that equalizes the urging force produced by the urging member in the circumferential direction is enhanced and tilting of the restraining member is suppressed. Therefore, the contact between the restraining gear and the locking protrusion can be prevented and the major causes of an undesirable sound and a hindrance to the rotation of the reel can be eliminated.
(4) The tooth of the restraining gear has two inclined faces which have an apex angle and interior angles, the apex angle being between an apex angle of the locking tooth portion of the reel and 90 degrees, and the interior angles being 30 degrees or greater with respect to a vertical line and also being approximately the same. That is, the interior angles are within 45 degrees. With this, in the meshed state between the restraining gear and the locking tooth portion, the reel can be reliably locked. Even if the two are shifted in phase when locked and therefore the reel is moved in the reverse winding direction, the extent of movement will be slight and therefore the slack of the magnetic tape will also be slight. Also, even if the reel is moved in the winding direction because of the mesh between the two, the extent of movement will be slight and therefore a pulling force that is exerted on the magnetic tape by the movement of the reel 2 will be small. Therefore, the disengagement of the magnetic tape from the tape leader pin due to forced locking can be prevented.
(5) When the reel is rotated in the winding direction by falling shock, etc., and an excessive pulling force is exerted on the magnetic tape, the restraining member is moved in the unlocking direction by the inclined face of the locking tooth portion which faces in the reverse winding direction. As a result, the meshed state between the restraining member and the locking tooth portion becomes shallow and the rotation of the reel in the reverse winding direction is allowed. Therefore, an excessive pulling force can be alleviated and the disengagement of the magnetic tape from the tape leader pin can be prevented.
(6) The apex angle of the tooth of the restraining gear of the restraining member is set to an angle greater than the apex angle of the locking tooth portion of the reel. That is, the tooth edge of the locking tooth portion of the reel is made thinner by setting the apex angle of the locking tooth portion to an angle less than the apex angle of the tooth of the restraining gear of the restraining member. As a result, the locking tooth portion becomes easy to deform, and slight play can be provided between the teeth. Therefore, a force to pull the magnetic tape can be alleviated without reducing the forced locking function. Particularly, in the case where the restraining gear and the locking tooth portion are formed from synthetic resin material, the function of alleviating the pulling force to be exerted on the magnetic force is enhanced because they are easily deformable.
(7) Thus, according to the present invention, reliable locking of the reel in the non-operative state, and alleviation of a magnetic-tape pulling force that is produced in the locked state by falling shock, etc., are compatible with each other. This can enhance reliability, while preventing stretching and disengagement of the magnetic tape and assuring magnetic recording-reproducing characteristics and a correct operation of loading the magnetic tape.